1. Field of the Invention
The invention relates to the field of automotive electrical systems. Specifically, the invention is directed to a system and method for protecting a component of an I.C. engine system by controlling a starter/alternator in response to the component""s temperature.
2. Description of the Related Art
A recent trend in automotive electrical systems is the combining of the formerly separately functioning and operating starter and alternator/generator components. As automobiles become more electronics intensive, in terms of electronic accessories and sophistication of control systems, the need becomes greater for increased electrical supply. As a result, the alternator has become physically larger and more powerful as automotive electrical needs have increased.
In addition, the need for increasing operating efficiencies from I.C. engines mandates a powerful and frequently operated starter motor to resume I.C. engine operation on short demand cycles. And, while these separate trends have been in place, a third element always present in automotive design is packaging efficiency in terms of underhood space. As these trends have progressed, a commonly proposed strategy is to combine the starter and alternator/generator into a single underhood element. In this regard, the starter function of the starter/alternator can be quite powerful vis-à-vis the I.C. engine being started inasmuch as the I.C. engine is required to achieve self-sustaining operation within xc2xd to 1 second of starter initiation and require significant demand of the battery. Furthermore, because of the increased demand of vehicle electrical systems, the capacity of the alternator is large and may generate substantial current during generation mode. In the event of system or component malfunction, or other unforeseen condition, a component can be caused to overheat while operating in either the starting mode or generation mode.
The present invention is directed to solving at least one of the potential problems associated with the trend towards combined starter and generator/alternator functions and short demand cycle I.C. engine operation. Specifically, the present invention is directed to a system and method for protecting a component of an I.C. engine system by controlling a starter/alternator in response to the component""s temperature. The system describes a method of comparing the temperature of the component to a predetermined threshold temperature and, if the temperature exceeds the threshold, disabling the starter/alternator. According to the present invention such components may include, but not be limited to, the vehicle""s battery, starter/alternator motor, and starter/alternator inverter. The starter/alternator is controlled/disabled according to mode of operation.